Draft device for steam-boilers.



I PATENTEDOCT. 13, 1903.

R. B. EGBGB. DRAFT DEVIUE FOR STEAM BOILERS.

rymm'rxou FILED JUNE 20, 1902.

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' ROBERT B. HODGE, OFBUFFALO, NEW

Patented October I3, 1903.

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DRAFT DEVIC FOR STEAM-BOILERS.

SPECIFICATION forming part ofl Letters Patent No. 741,037, dated October 173, 1903.

application filed June 20, 1902. Serial No. 112,401. (No model.)

To LZZ whom t may concern:

Be it known that I, ROBERT B, Honor., a citizen of the United States, residing at Buffalo, in the county of Erie and State of New York, have invented new and useful Improvements in Draft Devices for Steam-Boilers, of which the following is a specication.

This invention relates to'a draft-producing device designed more particularly for the smoke-stacks of marine boilers; but the same is also applicable to otherv types of boilers.

The object of myinvention is to provide an efficient and economical device of this kind which increases the draft and cools the stack, which can be applied to an ordinary stack Without requiring any departure from its usual form or construction, and which at the same time oers as small an obstruction in the stack as possible, so as not to interfere materially with the natural draft when the draft device is not used or becomes temporarily unserviceable.

In the accompanying drawings, Figure l is a vertical section through the smoke box and stack of a marine boiler provided with my improved draft device. Fig. 2 is a similar section at right angles to Fig. l.

Similar letters indicate similar'parts in both figures.

Aindicates the front smoke box or uptake of the boiler, provided centrally in its bottom with the usual arch A', and B indicates the stack rising from said box.

The draftinducing device consists of a horizontal fau C, arranged in the lower portion of the stack and secured to a vertical shaft D, which extends downwardly through the smoke-box and the arch A'. This shaft is journaled at its upper end in an open frame or bridge-tree E, secured horizontally within the stack, preferably above the fan, while its lower'portion turns in bearings ff', carried by thearch A and a bracket F, which latter is secured to a shelf F', extending across the base of the arch. The fan shaft may be driven by an engine or motor of any suitable construction. I prefer to employ a small oscillating steam-engine G, which has its piston-rod g connected with -a crank g', secured to the lower end ofthe fan-shaft. This engine is arranged in the space or recess formed by the arch A and the shelf F and is sup-- plied with steam by a pipe H, having a handvalve h. A iiy-wheel i is applied to the fanshaft, preferably Within said recess.

In the use of the devicethe fan produces a vigorous upward current through the stack, which not only increases the force of the draft,but also cools the stack. Itis well known that the efficiency ofthe draft is impaired by the heating of the stack, and it has been demonstrated that astack provided with my improved appliance remains comparatively cool, thus maintaining the most favorable condition for an efficient draft.

By locating the fan at or near the base of the stack, as shown, it is brought in close proximity to the smoke-box, where it is most effective, and by arranging its driving mechanismroutside of and below the smoke-box it is not exposed to the smoke and soot issuing from the stack and not liable to become clogged by the same. This arrangementalso renders the apparatus applicable to any ordinary stack without requiring a change or reconstruction of the same.

My improved arrangement has the further important advantage that it permits a practically free and unobstructed draft through the stack regardless of whether the fan is in motion or at rest. This is a desirable freature, as it permits the draft device to be used or not, according to the prevailing conditions of Wind and temperature.V For example, on a vessel it is desirable to stimulate the draft artificially in quiet or comparatively warm Weather, wh ile in cold or windy Weather there is little or no occasion for using the draft device, because the natural draft is sufiicient.

I am vaware that prior to my invention it has been proposed to stimulate the draft through a smoke-stack by one or more fans journaled in the same or in a chamber communicating therewith, and I do not therefore claim, broadly,such anarticial-draft device.

I claim Aas my inventionl. The combination with the smoke-stack of a steamboiler,of an upright shaft arranged in the stack and extending downwardly below the base of the same', fan-blades mounted horizontally on the portion of the shaft within the stack, and driving mechanism for said ICQ shaft supported independently of the stack and arranged below the base thereof, substantially as set forth.

2. The combination with the smoke-stack of a steam-boiler, of a bridge-tree arranged in the lower portion of the stack, a vertical shaft arranged in the stack, journaled at its upper end/in said bridge-tree and extending below the base of the stack,fanblades mounted horizontally on the portion of the shaft within the stack, a support arranged below the base of the stack, and driving mechanism mounted on said support and connected with the lower portion of said shaft, substantially as set forth.

3. The combination with a boiler smoke- Witnesses:

GEO. F. STILPHEN, ROBERT O. HODGE. 

